The present invention relates to a two-color image recorder such as a two-color digital copier.
Copiers known in the art include an automatic two-color digital copier capable of reproducing, for example, a red image component of an original document in distinction from a black image component which is printed on the white background of the document together with the red component. Specifically, this kind copier is generally constituted by a scanning section and a printing section. The scanning section includes two reading means which are operable at the same time for reading an image, and at least one of the reading means has a function of reading an image while omitting an image component of particular color (i.e. by regarding it identical with the background) by means of a color separating filter or the like. Image data outputted by the two reading means are processed by signal processor means to distinguish the image data associated with the particular color from the other data, e.g. black/white image data. These two kinds of data are fed at the same time to the printing section which is operable with the principle of electrophotography and is provided with, for example, a red and a black developing unit. As a result, a two-color copy is produced by a developing process which is effected in each of the different colors with a single paper. That is, the copier adopts a two-color simultaneous reading and two-color simultaneous developing system.
A problem with the above-described prior art digital copier is that the two reading means installed in the scanning section make the structure of the scanning section and therefore that of the entire apparatus complicated while increasing the cost.
Generally, the color component other than the black and white components of a two-color original document is not limited to a red component. In the case that such a document is subjected to two-color copying and that one of the reading means includes a filter which is transparent for red only, the copier sometimes determines that the image component of particular color other than red is either the black component or the white background. Then, the copier fails to reproduce the document as a two-color copy, i.e., it fails to faithfully read the actual conditions of the document.